Projector with exhaust fans having intersecting exhaust directions

ABSTRACT

A liquid crystal projector device of the present invention includes a casing having disposed therein a lamp unit, an optical system for receiving light from the lamp unit to generate image light, and a power unit. An exhaust system for cooling an inside of the casing is attached to a side surface of the casing. The exhaust system includes a first exhaust fan and a second exhaust fan, which stand along the side surface of the casing. The first exhaust fan is placed toward the lamp unit, while the second exhaust fan is placed toward the power unit. Exhaust directions of both exhaust fans intersect each other.

The priority application Number 2005-209288 upon which this patentapplication is based is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a projector device adapted to guidelight from a light source to an optical system to generate image lightfor magnification projection on a forward screen.

2. Description of Related Art

A conventional projector device of this type includes a casing havingdisposed therein a lamp for serving as a light source, and an opticalsystem including a polarization beam splitter, a polarizing plate,liquid crystal panels, a projection lens, etc. An exhaust system isarranged along a wall surface in the casing. The exhaust system causesair inside the casing to flow to thereby prevent temperature rise insidethe casing (see JP 8-275096, A).

However, because the exhaust system is usually placed with an inletdirection thereof toward the lamp with a great heat amount, the exhaustsystem discharges high temperature air, so that a user could feeluncomfortable when touching the exhaust. Therefore, it is necessary torotate an exhaust fan at a high speed in order to lower the exhausttemperature. This has resulted in a problem of increased noise occurringfrom the exhaust system.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a projector deviceadapted to lower the exhaust temperature without rotating the exhaustfan at a high speed.

A projector device of the present invention includes a casing havingdisposed therein a light source and an optical system for receivinglight from the light source to generate image light, the casing having awall surface having attached thereto an exhaust system for cooling aninside of the casing.

The exhaust system includes a first exhaust fan and a second exhaustfan, which stand along the wall surface of the casing, the first exhaustfan being placed with an inlet direction thereof toward the lightsource, with the second exhaust fan being placed with an inlet directionthereof toward an area deviating from the light source, both exhaustfans having exhaust directions intersecting each other.

Specifically, the second exhaust fan is placed with the inlet directiontoward a power unit arranged in a position spaced apart from the lightsource.

With the projector device of the present invention, because the firstexhaust fan included in the exhaust system is placed with the inletdirection toward the light source, the first exhaust fan draws hightemperature air emitted from the light source. On the other hand, thesecond exhaust fan draws lower temperature air than that of the airdrawn by the first exhaust fan because the second exhaust fan is placedwith the inlet direction toward the area deviating from the lightsource. Because the exhaust directions of both exhaust fans intersecteach other, the air drawn from the first exhaust fan and the air drawnfrom the second exhaust fan are mixed and then discharged. Consequently,the exhaust temperature is lower than that of the conventional projectordevice.

Therefore, according to the projector device of the present invention,an exhaust temperature equal to or lower than that of the conventionalone can be achieved at a rotation speed lower than that of the exhaustfan of the conventional exhaust system. This allows reduced noiseoccurring from the exhaust system.

Specifically, an intersection angle between an exhaust direction of thefirst exhaust fan and an exhaust direction of the second exhaust fan isset in a range of 40 degrees to 60 degrees.

The more increases the intersection angle between the exhaust directionof the first exhaust fan and the exhaust direction of the second exhaustfan, the larger is a necessary space inside the casing for mounting bothexhaust fans. Accordingly, in order to find the intersection anglebetween the exhaust direction of the first exhaust fan and the exhaustdirection of the second exhaust fan that gives the maximum exhausttemperature-lowering effect, an experiment was conducted wherevariations in exhaust temperature are measured with the intersectionangle as a parameter. The result is that the intersection angle within arange of 40 degrees to 60 degrees gives the maximum exhausttemperature-lowering effect.

That is, if the intersection angle is smaller than 40 degrees, then theair drawn from both exhaust fans is discharged without sufficientlymixed. Consequently, high temperature air is discharged from the firstexhaust fan side of the exhaust system, and low temperature air isdischarged from the second exhaust fan side.

In contrast, when the intersection angle is in the range of 40 degreesto 60 degrees, the high temperature air drawn from the first exhaust fanand the low temperature air drawn from the second exhaust fan aresufficiently mixed. Consequently, sufficient lowering effect for theexhaust temperature can be achieved.

However, if the intersection angle is greater than 60 degrees, thelowering degree of the exhaust temperature relative to the increase ofthe intersection angle is smaller than in the case where theintersection angle is in the range of 40 degrees to 60 degrees. If theintersection angle approximates 90 degrees, then the high temperatureair drawn from the first exhaust fan and the low temperature air drawnfrom the second exhaust fan hit each other. This inhibits a smoothrearward flow of air.

Therefore, according to the above specific configuration, the exhausttemperature can be lowered while minimizing enlargement of the devicedue to an increased mounting space for the exhaust system.

Specifically, the first exhaust fan and the second exhaust fan are eachattached with an inclination angle relative to the wall surface of thecasing. If one of the first and second exhaust fans is placed parallelwith the wall surface of the casing, for example, the other fan must beplaced greatly inclinedly relative to the wall surface of the casing,requiring a large space for mounting the exhaust system. In contrast,with the above specific configuration, the first exhaust fan and thesecond exhaust fan have the same or approximately same inclination anglerelative to the wall surface of the casing, thereby keeping thenecessary space for mounting the exhaust system to the minimum.

Further specifically, the projector device of the present invention isadapted to change intensity of the light emitted from the light sourceto a plurality of levels, and includes control means for variablysetting revolutions of the first exhaust fan and/or the second exhaustfan depending on the intensity of the light. With the specificconfiguration, the projector device has a low power consumption modewhere the power consumption is reduced by lowering the intensity of thelight emitted from the light source. When the low power consumption modeis set, the noise occurring from the exhaust system can be furtherreduced by reducing the revolutions of the first and second exhaustfans.

As described above, according to the projector device of the presentinvention, the exhaust temperature can be lowered without rotating theexhaust fan at a high speed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a liquid crystal projector device of thepresent invention;

FIG. 2 is a perspective view showing the liquid crystal projector devicewith an upper half case thereof removed therefrom;

FIG. 3 is an exploded perspective view showing the liquid crystalprojector device with the upper half case removed therefrom;

FIG. 4 is an exploded perspective view of the liquid crystal projectordevice;

FIG. 5 illustrates an optical system of the liquid crystal projectordevice;

FIG. 6 is a sectional view of a latter stage slit plate and apolarization beam splitter;

FIG. 7 is a perspective view showing a former stage slit plate, a secondintegrator lens, the latter stage slit plate and the polarization beamsplitter;

FIG. 8 is an exploded perspective view of an optical system holdingcase, a light synthesizer and a cooling unit;

FIG. 9 is an exploded perspective view of the light synthesizer and thecooling unit;

FIG. 10 is a front view showing an incidence side polarizing plate;

FIG. 11 is a graph representing a relationship between an area ratio ofa glass to the polarizing plate and a polarizing plate temperature;

FIG. 12 is a perspective view of the optical system holding case;

FIG. 13 is a plan view of the optical system holding case;

FIG. 14 is an exploded perspective view showing the optical systemholding case having optical components placed therein with the formerstage and latter stage slit plates removed therefrom;

FIG. 15 is a perspective view showing the optical system holding casehaving optical components placed therein;

FIG. 16 is an exploded perspective view showing the optical systemholding case and a first integrator lens holder;

FIG. 17 is an exploded perspective view for illustrating a method forattaching the first integrator lens holder to the optical system holdingcase;

FIG. 18( a) and FIG. 18( b) are a sectional view showing the opticalsystem holding case having a lens holder for 0.6 inch attached theretoand a lens holder for 0.7 inch attached thereto, respectively;

FIG. 19 is a plan view of the cooling unit;

FIG. 20 is a perspective view of a housing of the cooling unit;

FIG. 21 is an exploded perspective view of the housing;

FIG. 22 is a plan view of a lower housing half constituting the housing;

FIG. 23 is an exploded perspective view showing a lamp cooling fan beingattached to the optical system holding case;

FIG. 24 is a horizontal sectional view of a lamp unit;

FIG. 25 is a vertical sectional view of the lamp unit;

FIG. 26 is a perspective view of an exhaust system; and

FIG. 27 is a perspective view showing the exhaust system with a fancover thereof removed therefrom.

DETAILED DESCRIPTION OF THE INVENTION

The present invention embodied in a liquid crystal projector device willbe specifically described below with reference to the drawings. In thedescription given below, the image projection direction of the liquidcrystal projector device shown in FIG. 1 is defined as the forwarddirection, and right and left are defined by facing the front face ofthe liquid crystal projector device.

Overall Construction

As shown in FIG. 1, the liquid crystal projector device of the presentinvention includes a flat casing 1 including a lower half case 12 and anupper half case 11. A manipulation portion 15 including a plurality ofmanipulation buttons is disposed on a surface of the casing 1, while aprojection window 13 is provided on the front face of the casing 1. Avent 14 for discharging the air in the casing 1 to the outside isprovided on the right side wall of the casing 1.

As shown in FIG. 2 and FIG. 3, a synthetic resin optical system holdingcase 7 extending in an approximate L-shape is disposed inside the casing1. Disposed inside the optical system holding case 7 are a lamp unit 4for serving as a light source, an optical system 2 (see FIG. 5) forseparating white light emitted from the lamp unit 4 into light of threeprimary colors, and an image synthesizer 3 for irradiating liquidcrystal panels for three primary colors with the light of three primarycolors to generate image light of three primary colors, and synthesizingthe generated image light of three primary colors into color imagelight. The lamp unit 4 is contained at the right end in the opticalsystem holding case 7, while the image synthesizer 3 is contained at theforward end in the optical system holding case 7. The optical system 2is disposed on a light path in the optical system holding case 7 fromthe lamp unit 4 to the image synthesizer 3.

The optical system holding case 7 has a forward end edge thereof coupledto the base end of a cylinder 39 a for holding a projection lens 39.Further, a power unit 9 is placed inside the casing 1 at the forwardside of the optical system holding case 7.

As shown in FIG. 2, an exhaust system 6 including a first exhaust fan 61and a second exhaust fan 62 is attached to the right side wall of thelower half case 12. The first exhaust fan 61 is placed with an inletdirection thereof toward the lamp unit 4, while the second exhaust fan62 is placed with an inlet direction thereof toward the power unit 9.

As shown in FIG. 4, a cooling unit 5 for cooling the image synthesizer 3is disposed below the image synthesizer 3. The cooling unit 5 includes afirst fan 52 and a second fan 53. Bottom inlet windows (not shown) arerespectively provided on the bottom wall of the lower half case 12 formounting the first fan 52 and the second fan 53 thereon. Air from bothcooling fans 52, 53 is blown to the image synthesizer 3 through achannel formed in a housing 54 of the cooling unit 5.

The liquid crystal projector device of the present invention will bedescribed below in detail in construction.

Optical System 2

As shown in FIG. 5, white light from the lamp unit 4 is guided through afirst integrator lens 21, a former stage slit plate 23, a secondintegrator lens 22, a latter stage slit plate 24, a polarization beamsplitter 25 and a field lens 20 to a first dichroic mirror 26.

The first integrator lens 21 and the second integrator lens 22 are madeof a heat resistance glass fly-eye lens, and have a function ofuniformizing illuminance distribution of the white light emitted fromthe lamp unit 4. The former stage slit plate 23 and the latter stageslit plate 24 are made of an aluminum thin plate, and have a function ofblocking unnecessary incident light toward the polarization beamsplitter 25.

As shown in FIG. 6, the polarization beam splitter 25 includes apolarizing plate 25 a and a half-wavelength plate 25 b with slits joinedto a light emergence surface thereof. The latter stage slit plate 24 isattached in close contact with a light incidence surface of thepolarizing plate 25 a.

Inside the polarizing plate 25 a, first interfaces 125 for passingtherethrough a P-wave of light incident on the polarizing plate 25 a andreflecting an S-wave, and second interfaces 126 for reflecting forwardthe S-wave reflected by the first interfaces 125 are alternately formedwith an inclination angle of 45 degrees relative to the surface of thepolarizing plate 25 a. Each slit 24 a of the latter stage slit plate 24is provided in a position that allows light incidence on each of thefirst interfaces 125, but light incidence on the second interfaces 126is prevented by the latter stage slit plate 24.

The P-wave of the light incident on the first interfaces 125 passesthrough the first interfaces 125 to reach the half-wavelength plate 25b. The P-wave has a phase thereof inversed by further passing throughthe half-wavelength plate 25 b, and emerges as an S-wave. On the otherhand, the S-wave reflected by the first interfaces 125 reaches thesecond interfaces 126, and is reflected by the second interfaces 126 toemerge from each slit 25 c of the half-wavelength plate 25 b. Thus, onlythe S-waves emerge from the polarization beam splitter 25.

As shown in FIG. 5, the light having passed through the polarizationbeam splitter 25 reaches through the field lens 20 to the first dichroicmirror 26. The first dichroic mirror 26 has a function of reflectingonly a blue component of light and passing red and green componentstherethrough. A second dichroic mirror 27 has a function of reflectingthe green component of light and passing the red component therethrough,and a field mirror 28 has a function of reflecting the red component.Thus, the white light emitted from the lamp unit 4 is separated by thefirst and second dichroic mirrors 26, 27 into blue light, green lightand red light, and guided to the image synthesizer 3.

An optical system of the conventional liquid crystal projector devicefails to include the former stage slit plate 23 included in the opticalsystem 2 of the liquid crystal projector device of the present inventionshown in FIG. 2.

FIG. 6 illustrates the polarization beam splitter 25 of the presentinvention. Because a polarization beam splitter 25 of the conventionalliquid crystal projector device has the same configuration, theconventional liquid crystal projector device will be described withreference to the same drawing.

Because the polarization function of the polarization beam splitter 25is insufficiently performed if light is incident on the secondinterfaces 126 of the polarization beam splitter 25, the latter stageslit plate 24 is placed in contact with a light incidence surface of thepolarization beam splitter 25, or in a position close to the surface, inorder to maintain relative position accuracy between the firstinterfaces 125 of the polarization beam splitter 25 and respective slits24 a of the latter stage slit plate 24.

The polarization beam splitter 25 significantly degrades thepolarization function upon exceeding a limit temperature, and thereforeneeds to be used in a range within the limit temperature. However, heatis transmitted to the polarization beam splitter 25 from the latterstage slit plate 24, which could have a high temperature upon receipt oflight from the lamp unit 4, because the latter stage slit plate 24 isplaced in contact with the light incidence surface of the polarizationbeam splitter 25, or in a position close to the surface. This has causeda problem of the polarization beam splitter 25 having a high temperatureexceeding a limit temperature.

In contrast, with the liquid crystal projector device of the presentinvention, the former stage slit plate 23 is arranged as shown in FIG. 7on the light path of the optical system 2 in a position spaced apartfrom the latter stage slit plate 24 toward the lamp unit 4, and aplurality of slits 23 a are provided in the former stage slit plate 23at a plurality of locations overlapping in the optical axis directionwith the respective slits 24 a of the latter stage slit plate 24.Therefore, unnecessary incident light toward the polarization beamsplitter 25 is largely blocked by the former stage slit plate 23. Thisallows the latter stage slit plate 24 to receive a less amount ofunnecessary light than conventional one, resulting in prevention of thelatter stage slit plate 24 having a high temperature exceeding a limittemperature.

Although the former stage slit plate 23 may have a high temperature uponreceipt of light from the lamp unit 4, only slight heat is transmittedfrom the former stage slit plate 23 to the polarization beam splitter25, not only because the former stage slit plate 23 is placed in aposition spaced apart from the polarization beam splitter 25, but alsobecause the heat resistant glass second integrator lens 22 with a lowcoefficient of thermal conductivity intervenes between the former stageslit plate 23 and the polarization beam splitter 25.

Therefore, according to the optical system 2 of the liquid crystalprojector device of the present invention, temperature rise of thepolarization beam splitter 25 can be suppressed to the minimum.Consequently, the polarization beam splitter 25 is prevented from havinga high temperature exceeding a limit temperature.

Image Synthesizer 3

As shown in FIG. 8 and FIG. 9, the image synthesizer 3 includes a liquidcrystal panel for blue 33 b, a liquid crystal panel for green 33 g and aliquid crystal panel for red 33 r, which are attached to three sidefaces of a cube-like color synthesis prism 31, respectively.

As shown in FIG. 8, the image synthesizer 3 is contained in the opticalsystem holding case 7 through an opening 172 provided in a lid 7 a ofthe optical system holding case 7.

As shown in FIG. 2, incidence polarizing plate holders 36 b, 36 g, 36 rare attached to light incidence sides of the three liquid crystal panels33 b, 33 g, 33 r, respectively. The incidence polarizing plate holders36 b, 36 g, 36 r hold three incidence polarizing plates 32 b, 32 g, 32 rdescribed later.

The blue light reflected by the first dichroic mirror 26 and a fieldmirror 29 a shown in FIG. 5 is guided by a field lens 35 b through thefield lens 35 b, the incidence polarizing plate for blue 32 b, theliquid crystal panel for blue 33 b and an emergence polarizing plate forblue 34 b to the color synthesis prism 31.

The green light reflected by the second dichroic mirror 27 is guided bya field lens 35 g through the field lens 35 g, the incidence polarizingplate for green 32 g, the liquid crystal panel for green 33 g and anemergence polarizing plate for green 34 g to the color synthesis prism31.

Similarly, the red light reflected by two field mirrors 28, 29 b isguided by a field lens 35 r of the image synthesizer 3 through the fieldlens 35 r, the incidence polarizing plate for red 32 r, the liquidcrystal panel for red 33 r and an emergence polarizing plate for red 34r to the color synthesis prism 31.

The image light of the three colors guided to the color synthesis prism31 is synthesized by the color synthesis prism 31, and the resultingcolor image light is to be magnifyingly projected through the projectionlens 39 on a forward screen.

As shown in FIG. 10, the incidence polarizing plate for blue 32 b, theincidence polarizing plate for green 32 g and the incidence polarizingplate for red 32 r each include a glass base material 32 a made ofsapphire glass and a synthetic resin polarizing film 32 c joined to asurface thereof. Each of the incidence polarizing plates 32 b, 32 g, 32r will generate heat upon receipt of light. Because the polarizationfunction significantly degrades if the temperature of the polarizingfilm 32 c exceeds a limit temperature, the cooling unit 5 shown in FIG.8 and FIG. 9 blows outside air to thereby cool each of the incidencepolarizing plates 32 b, 32 g, 32 r.

However, it is necessary in the conventional liquid crystal projectordevice to rotate cooling fans of the cooling unit 5 at a high speed inorder to keep the temperature of the polarizing film 32 c within a limittemperature. This has resulted in a problem of increased noise occurringfrom the cooling unit 5.

Accordingly, in order to attempt to lower the temperature of each of theincidence polarizing plates 32 b, 32 g, 32 r by enlarging the area ofthe glass base material 32 a, i.e. the heat dissipation area, anexperiment was conducted where a plurality of kinds of incidencepolarizing plates for green 32 g with a constant area of the polarizingfilm 32 c but different areas of the glass base material 32 a wereprepared, and each of the plurality of kinds of incidence polarizingplates for green 32 g is attached to the liquid crystal projector devicefor measurement of the temperature of the polarizing film 32 c in use.The polarizing film 32 c is of a size of 20.8 mm×16.3 mm, and the roomtemperature is 27° C. Table 1 given below and FIG. 11 show theexperimental result.

TABLE 1 Area Ratio of Glass Temperature of Size of Glass Base BaseMaterial to Polarizing Film Material [mm × mm] Polarizing Film [%] [°C.] 30.0 × 24.0 224 61.4 27.8 × 21.8 178 61.6 26.8 × 20.8 163 63.2 26.3× 20.3 157 64.2 25.8 × 19.8 150 63.5 24.8 × 18.8 137 65.0

FIG. 11 reveals that the temperature of the polarizing film 32 c isstable at relatively low temperatures when the area ratio of the glassbase material 32 a to the polarizing film 32 c is set to 178% or more.On the other hand, it is understood that temperature rise of thepolarizing film 32 c is significant when the area ratio is set to 150%or less.

Further, it is understood that temperature variations of the polarizingfilm 32 c relative to the area ratio are unstable when the area ratio isset to 150%-178%. This is probably because the amount of heattransmission from the polarizing film 32 c to the glass base material 32a approximately balances with the amount of heat dissipation from theglass base material 32 a. Therefore, the magnitude relation of bothcould be reversed by slight variation of the heat transmission amountand/or heat dissipation amount due to certain factors. This rendersunstable the temperature variations of the polarizing film 32 c relativeto the area ratio.

Considering the above experimental result, the reason why thetemperature rise of the polarizing film 32 c is significant when thearea ratio is set to 150% or less is probably that the amount of heatdissipation from the glass base material 32 a is smaller than the amountof heat transmission from the polarizing film 32 c to the glass basematerial 32 a.

Heat of the polarizing film 32 c is first transmitted to a central areaof the glass base material 32 a having the polarizing film 32 c joinedthereto, and then gradually transmitted from the central area to asurrounding peripheral area. However, because the glass base material 32a has a low coefficient of thermal conductivity, even if heat isgenerated in the polarizing film 32 c, there is little temperature risein the peripheral area, which is in a certain distance away from thecentral area of the glass base material 32 a. This allows only a slightamount of heat dissipation from the peripheral area.

Therefore, the reason why the polarizing film 32 c has an approximatelyconstant temperature when the area ratio is set to 178% or more isprobably that enlargement of the surface area of the glass base material32 a fails to lead to enlargement of the heat dissipation area.

Accordingly, based on the above experimental result, the area ratio ofthe glass base material 32 a to the polarizing film 32 c is set to 178%,where the temperature of the polarizing film 32 c is stable atrelatively low temperatures, with the glass base material 32 a having aminimum surface area. The size of the polarizing film 32 c of theincidence polarizing plate for blue 32 b, the incidence polarizing platefor green 32 g and the incidence polarizing plate for red 32 r is set to20.8 mm×16.3 mm, with the size of the glass base material 32 a being27.8 mm×21.8 mm.

This allows cooling fans of the cooling unit 5 to have reducedrevolutions, resulting in reduced noise occurring from the cooling unit5.

Optical System Holding Case 7

The former stage slit plate 23, the second integrator lens 22, thelatter stage slit plate 24, the polarization beam splitter 25, the fieldlens 20, the first and second dichroic mirrors 26, 27 and the threefield mirrors 28, 29 a, 29 b, which constitute the optical system 2shown in FIG. 5 are placed in the optical system holding case 7 made ofa synthetic resin integral mold shown in FIG. 12 and FIG. 13. The lampunit 4 is contained at the right end in the optical system holding case7, while a space 70 is formed at the forward end of the optical systemholding case 7. The above described image synthesizer 3 is to be placedinside the space 70.

The optical system holding case 7 has both walls along the light pathfrom the lamp unit 4 to the image synthesizer 3, which are formed with afirst setting groove 71 for setting therein the former stage slit plate23 shown in FIG. 5, a second setting groove 72 for setting the secondintegrator lens 22 therein, a third setting groove 73 for settingtherein the latter stage slit plate 24 and the polarization beamsplitter 25 together, a fourth setting groove 74 for setting the fieldlens 20 therein, fifth and sixth setting grooves 75, 76 for settingtherein the first and second dichroic mirrors 26, 27, respectively, andseventh to ninth setting grooves 77, 78 a, 78 b for setting therein thethree field mirrors 28, 29 a, 29 b, respectively.

FIG. 14 and FIG. 15 show the former stage slit plate 23, the secondintegrator lens 22, the latter stage slit plate 24, the polarizationbeam splitter 25, the field lens 20, the first and second dichroicmirrors 26, 27 and the three field mirrors 28, 29 a, 29 b, whichconstitute the optical system 2, being set in the setting grooves 71-78b, respectively.

The liquid crystal projector device of the present invention is adaptedto interchangeably use a liquid crystal panel with a diagonal length of0.6 inch and a liquid crystal panel of 0.7 inch for the three liquidcrystal panels 33 r, 33 g, 33 b shown in FIG. 5.

A distance between the first integrator lens 21 and the secondintegrator lens 22 shown in FIG. 5 needs to be changed depending on thesize of the liquid crystal panel to be used. With the conventionalliquid crystal projector device, two grooves spaced apart from eachother along the light path are formed on both walls of the opticalsystem holding case, so that the first integrator lens 21 and the secondintegrator lens 22 are respectively held by the two grooves. However, inorder to allow a plurality of kinds of liquid crystal panels differentin size to be used, it is necessary to prepare a plurality of kinds ofoptical system holding cases different in distance between the twogrooves. This has resulted in increased design time and productioncosts.

In contrast, the liquid crystal projector device of the presentinvention is so adapted that the optical system holding case 7 hasinterchangeably attached thereto two kinds of lens holders for holdingthe first integrator lens 21, namely, a lens holder for 0.6 inch 8 ashown in FIG. 18( a) and a lens holder for 0.7 inch 8 b shown in FIG.18( b). Because the lens holder for 0.6 inch 8 a and the lens holder for0.7 inch 8 b have the same configuration except that the position of apositioning pin described later is different, only the lens holder for0.6 inch 8 a will be described, and the lens holder for 0.7 inch 8 bwill not be described.

As shown in FIG. 16, the lens holder for 0.6 inch 8 a includes a platemetal rectangular frame 82 for holding the first integrator lens 21, anda pair of plate metal attachment plates 83 a, 83 b extending from theframe 82 along the upper face and lower face of the optical systemholding case 7. A pair of positioning pins 81, 81 are protrudeddownwardly on each of the pair of attachment plates 83 a, 83 b.

As shown in FIG. 14 and FIG. 15, the upper wall of the optical systemholding case 7 is provided with an insertion opening 180 for insertingtherethrough the former stage slit plate 23, the second integrator lens22, the latter stage slit plate 24, the polarization beam splitter 25and the field lens 20.

As shown in FIG. 16, a top plate 179 for closing the insertion opening180 is attached to the upper wall of the optical system holding case 7.The top plate 179 is provided with an opening 171 for inserting bothlens holders 8 a, 8 b therethrough, and positioning holes 78, 78 forpositioning both lens holders 8 a, 8 b. The positioning pins 81, 81protruded on the upper attachment plate 83 a for both lens holders 8 a,8 b are to be fitted into the positioning holes 78, 78 of the top plate179.

Similarly, the bottom wall of the optical system holding case 7 is alsoprovided with positioning holes 78, 78. The positioning pins 81, 81protruded on the lower attachment plate 83 b are to be fitted into thepositioning holes 78, 78.

As shown in FIG. 17, each of both lens holders 8 a, 8 b is fixed to thetop plate 179 by screws 182, 182 with the positioning pins 81, 81protruded on the upper attachment plate 83 a fitted into the positioningholes 78, 78 of the top plate 179. Then, the positioning pins 81, 81protruded on the lower attachment plate 83 b for both lens holders 8 a,8 b are fitted into the positioning holes 78, 78 of the bottom wall ofthe optical system holding case 7, and thereafter the top plate 179 isfixed to the upper wall of the optical system holding case 7 by screws181, 181 to thereby attach the first integrator lens 21 to apredetermined position on the light path.

The positioning pins 81, 81 of the holder for 0.7 inch 8 b shown in FIG.18( b) are protruded in positions spaced apart from the frame 82 morethan the respective positioning pins 81, 81 of the holder for 0.6 inch 8a shown in FIG. 18( a). Distances S3 and S4 between both positioningpins 81, 81 of the holder for 0.7 inch 8 b shown in FIG. 18( b) and thesurface of the first integrator lens 21 attached to the frame 82 arethereby made greater than distances S1 and S2 between both positioningpins 81, 81 of the holder for 0.6 inch 8 a shown in FIG. 18( a) and thesurface of the first integrator lens 21 attached to the frame 82.Consequently, a distance d2 between the first integrator lens 21 and thesecond integrator lens 22 when the holder for 0.7 inch 8 b is attachedis larger than a distance d1 when the holder for 0.6 inch 8 a isattached.

The above distance d1 is set to a distance suitable for a 0.6 inchliquid crystal panel, while the above distance d2 is set to a distancesuitable for a 0.7 inch liquid crystal panel.

Therefore, according to the liquid crystal projector device of thepresent invention, a plurality of kinds of liquid crystal panels withdifferent sizes can be used by only changing the lens holder for holdingthe first integrator lens 21 depending on the size of the liquid crystalpanel. Consequently, it is unnecessary to prepare a plurality of kindsof optical system holding cases, so that design time is shortened andproduction costs are reduced more than conventionally.

Cooling Unit 5

As shown in FIG. 4, FIG. 8 and FIG. 9, the cooling unit 5 for coolingthe image synthesizer 3 is placed below the image synthesizer 3.

With the conventional liquid crystal projector device, a cooling unit isprovided with cooling fans respectively exclusively used for liquidcrystal panels for red, green and blue constituting an imagesynthesizer, so that the three cooling fans cool the three liquidcrystal panels.

As shown in FIG. 5, with light path lengths from the lamp unit 4 to thethree liquid crystal panels 33 b, 33 g, 33 r, a light path for blue tothe liquid crystal panel for blue 33 b and a light path for green to theliquid crystal panel for green 33 g have the same length, while only alight path for red to the liquid crystal panel for red 33 r is longer.The liquid crystal panel for red 33 r receives light with the smallestintensity because the longer the light path is, the lower is intensityof light received by the three liquid crystal panels 33 b, 33 g, 33 r.

Because the three liquid crystal panels 33 b, 33 g, 33 r have variousheat amounts depending on intensity of light received by the respectiveliquid crystal panels 33 b, 33 g, 33 r, the liquid crystal panel forblue 33 b has the greatest heat amount, and the liquid crystal panel forred 33 r has the smallest heat amount.

Accordingly, attention has been focused on a difference between heatamounts of the three liquid crystal panels 33 b, 33 g, 33 r caused by adifference between the light path lengths. The liquid crystal projectordevice of the present invention omits the cooling fan conventionallyexclusively used for the liquid crystal panel for red 33 r with thesmallest heat amount out of the three cooling fans respectively providedfor the liquid crystal panels for red, green and blue, and includes thecooling unit 5 consisting of two cooling fans.

As shown in FIG. 19, the cooling unit 5 includes the first fan 52, thesecond fan 53, and the approximately T-shaped housing 54. The channelfor guiding outside air drawn from both cooling fans 52, 53 to the threeliquid crystal panels 33 b, 33 g, 33 r shown in FIG. 9 and the threeincidence polarizing plates 32 b, 32 g, 32 r shown in FIG. 5 is formedinside the housing 54. The first fan 52 and the second fan 53 are placedsuch that air discharge directions thereof intersect each other.

As shown in FIGS. 20 and 21, the housing 54 includes an upper housinghalf 54 a and a lower housing half 54 b joined to each other. Thehousing 54 is provided with a first attachment opening 57 for couplingthe first fan 52 and a second attachment opening 58 for coupling thesecond fan 53, which face in directions different by 90 degrees.

The upper housing half 54 a has an upper wall provided, in positionsadjacent to the first attachment opening 57, with a first outlet forblue 55 b for blowing air toward the incidence polarizing plate for blue32 b shown in FIG. 5, and a second outlet for blue 56 b for blowing airtoward the liquid crystal panel for blue 33 b. Provided in positionsadjacent to the second attachment opening 58 are a first outlet forgreen 55 g for blowing air toward the incidence polarizing plate forgreen 32 g shown in FIG. 5, and a second outlet for green 56 g forblowing air toward the liquid crystal panel for green 33 g.

Further, the upper wall of the upper housing half 54 a is provided, inpositions spaced apart from the first attachment opening 57 along achannel of air introduced from the first attachment opening 57, with afirst outlet for red 55 r for blowing air toward the incidencepolarizing plate for red 32 r shown in FIG. 5, and a second outlet forred 56 r for blowing air toward the liquid crystal panel for red 33 r.

On the other hand, as shown in FIG. 21 and FIG. 22, formed in the lowerhousing half 54 b are a first upstream side channel 151 extendingstraight from the first attachment opening 57 to the first outlet forblue 55 b and the second outlet for blue 56 b, a second upstream sidechannel 152 extending straight from the second attachment opening 58 tothe first outlet for green 55 g and the second outlet for green 56 g,and a downstream side channel 153 where the air having passed throughthe first and second upstream side channels 151, 152 joins together toreach the first outlet for red 55 r and the second outlet for red 56 r.

A first narrow portion 59 a is formed between the first upstream sidechannel 151 and the downstream side channel 153, while a second narrowportion 59 b is formed between the second upstream side channel 152 andthe downstream side channel 153.

Therefore, the amount of air that is introduced from the first fan 52 tothe first attachment opening 57 of the housing 54 and passes through thefirst upstream side channel 151 to flow into the downstream side channel153 is restricted to a certain amount due to channel resistanceoccurring in the first narrow portion 59 a. This causes the airintroduced from the first attachment opening 57 to be partiallydischarged from the first outlet for blue 55 b and the second outlet forblue 56 b, which are provided at the upper stream side than the firstnarrow portion 59 a. The incidence polarizing plate for blue 32 b andthe liquid crystal panel for blue 33 b can be thereby sufficientlycooled.

Similarly, the amount of air that is introduced from the second fan 53to the second attachment opening 58 of the housing 54 and passes throughthe second upstream side channel 152 to flow into the downstream sidechannel 153 is restricted to a certain amount due to channel resistanceoccurring in the second narrow portion 59 b. This causes the airintroduced from the second attachment opening 58 to be partiallydischarged from the first outlet for green 55 g and the second outletfor green 56 g, which are provided at the upper stream side than thesecond narrow portion 59 b. The incidence polarizing plate for green 32g and the liquid crystal panel for green 33 g can be therebysufficiently cooled.

The certain amount of air having passed through the first narrow portion59 a flows straight through the downstream side channel 153 toward thefirst outlet for red 55 r and the second outlet for red 56 r. Further,the certain amount of air having passed through the second narrowportion 59 b joins with the air flow through the downstream side channel153 toward the first outlet for red 55 r and the second outlet for red56 r. Consequently, the certain amount of air that has been introducedfrom the first attachment opening 57 and passed through the first narrowportion 59 a and the certain amount of air that has been introduced fromthe second attachment opening 58 and passed through the second narrowportion 59 b are discharged through the downstream side channel 153 fromthe first outlet for red 55 r and the second outlet for red 56 r. Theincidence polarizing plate for red 32 r and the liquid crystal panel forred 33 r can be thereby sufficiently cooled.

With the conventional liquid crystal projector device, the cooling unitincludes the three cooling fans respectively exclusively provided forthe liquid crystal panels for red, green and blue. However, according tothe above liquid crystal projector device of the present invention, theincidence polarizing plates 32 r, 32 g, 32 g and liquid crystal panels33 r, 33 g, 33 b for three colors can be sufficiently cooled using thetwo cooling fans 52, 53. This allows the device to be made smaller by amounting space for one omitted cooling fan, and also enables the totalpower consumption in operation to be reduced by a power consumption ofthe cooling fan.

Lamp Unit 4

As shown in FIG. 2, the lamp unit 4 is contained at the right end in theoptical system holding case 7. As shown in FIG. 23, an inlet housing 45is attached to a rear wall 174 at the right end of the optical systemholding case 7, and a lamp cooling fan 42 for cooling the lamp unit 4 isattached to an end of the inlet housing 45.

As shown in FIG. 24 and FIG. 25, the lamp unit 4 includes a reflector46, a lamp 41 provided at the focal position of the reflector 46, a lens47 disposed forward along the light emergence direction of the lamp 41,and a lamp housing 140 made of a rectangular frame, and is constructedby attaching the reflector 46 and the lens 47 to the opening of the lamphousing 140. The reflector 46 has a back surface thereof surrounded byfour side walls 174, 176, 177, 178 of the optical system holding case 7.

As shown in FIG. 24, the lamp unit 4 is contained at the right end inthe optical system holding case 7 with both side walls 140 a, 140 b ofthe lamp housing 140 in contact with both side walls 174, 176 of theoptical system holding case 7, respectively. An air introduction hole141 is provided in the rear side wall 140 a of the lamp housing 140. Anopening 49 a is provided in a rear side portion 46 a of the reflector 46in a position corresponding to the air introduction hole 141. A metalmesh filter 48 a is placed in the opening 49 a.

On the other hand, an air discharge hole 142 is provided in the frontside wall 140 b of the lamp housing 140 in a position opposed to the airintroduction hole 141. An opening 49 b is provided in a front sideportion 46 b of the reflector 46 in a position corresponding to the airdischarge hole 142. A metal mesh filter 48 b is placed in the opening 49b.

As shown in FIG. 23, the rear wall 174 at the right end of the opticalsystem holding case 7 is provided with a first intake 43, a secondintake 44 a and a third intake 44 b, which are for drawing air from thelamp cooling fan 42 into the optical system holding case 7. The firstintake 43 has a rectangular opening shape long in the vertical direction(width direction). The second intake 44 a and the third intake 44 b areformed in a rectangle having a width of approximately one-third of thatof the first intake 43. A wind blocking wall 44 c having a width ofapproximately one-third of that of the first intake 43 is definedbetween both intakes 44 a, 44 b by a part of the rear wall 174 of theoptical system holding case 7.

As shown in FIG. 24, the first intake 43 opens toward the airintroduction hole 141 of the lamp housing 140 and the opening 49 a ofthe reflector 46, and the second intake 44 a and the third intake 44 bopen toward the back surface of the reflector 46.

As shown in FIG. 23, a vent 170 is provided in a right side wall 175 atthe right end of the optical system holding case 7. As shown in FIG. 2,the first exhaust fan 61 included in the exhaust system 6 is placedfacing the vent 170. The vent 170 is formed inclinedly relative to theright wall surface of the lower half case 12 having the exhaust system 6attached thereto.

As shown in FIG. 2, the lower half case 12 has a rear wall thereofprovided with a back inlet 19 with slits. The lamp cooling fan 42 shownin FIG. 23 is placed facing the back inlet 19.

As shown in FIG. 24, air drawn from the back inlet 19 of the casing 1 bythe lamp cooling fan 42 is introduced through a channel in the inlethousing 45 from the first intake 43, the second intake 44 a and thethird intake 44 b toward the lamp unit 4.

The air having passed through the first intake 43 is introduced throughthe air introduction hole 141 of the lamp housing 140 and the meshfilter 48 a of the reflector 46 into the reflector 46, and dischargedthrough the opposite mesh filter 48 b and the air discharge hole 142from exhaust slits 173 to the outside of the optical system holding case7. The discharged high temperature air is sucked by the first exhaustfan 61, and discharged from the vent 14 of the casing 1 to the outsideof the casing 1.

On the other hand, because the wind blocking wall 44 c is providedbetween the second intake 44 a and the third intake 44 b as shown inFIG. 23, the air having passed through the second intake 44 a flowsalong the upper portion of the reflector 46, and the air having passedthrough the third intake 44 b flows along the lower portion of thereflector 46.

Then, the air flowing along the upper portion and lower portion of thereflector 46 is sucked by the first exhaust fan 61, and discharged fromthe vent 14 of the casing 1 to the outside of the casing 1.

The conventional liquid crystal projector device has no wind blockingwall 44 c shown in FIG. 23, so that air is sent from one large bloweropening where the second intake 44 a is continuous with the third intake44 b to thereby cool the lamp unit 4. However, there has been a problemof an upper wall 177 and a lower wall 178 of the optical system holdingcase 7 shown in FIG. 25, although a sufficient air volume is given,deteriorating and degrading due to heat emitted from the lamp unit 4.

An analysis of a reason for this reveals that because the air sent fromone blower opening largely flows along the back surface of the reflector46 in a middle portion in the vertical direction of the reflector 46,although some cooling effect can be achieved in the middle portion,sufficient cooling effect cannot be achieved in upper and lower areas ofthe reflector 46 near the upper wall 177 and lower wall 178 of theoptical system holding case 7.

Accordingly, with the liquid crystal projector device of the presentinvention, the above problem is solved by forcing the air delivered fromthe lamp cooling fan 42 to diverge toward the upper and lower areas ofthe reflector 46. The upper and lower areas of the reflector 46 can bethereby sufficiently cooled. Consequently, the temperature of the upperwall 177 and lower wall 178 of the optical system holding case 7 islower than that of the conventional liquid crystal projector device, andtherefore degradation due to deterioration of the optical system holdingcase 7 can be prevented.

Exhaust System 6

As shown in FIG. 2 and FIG. 3, the exhaust system 6 including the firstexhaust fan 61 and the second exhaust fan 62 is attached to the rightside wall of the lower half case 12. The first exhaust fan 61 is placedwith an inlet direction thereof toward the lamp unit 4, while the secondexhaust fan 62 is placed with an inlet direction thereof toward thepower unit 9. Exhaust directions of both exhaust fans 61, 62 intersecteach other.

As shown in FIG. 26 and FIG. 27, the exhaust system 6 has the firstexhaust fan 61 and the second exhaust fan 62 sandwiched between asynthetic resin fan holder 63 and a metal fan cover 64. A hook 66 to beengaged with a groove 65 provided in the upper wall and lower wall ofthe fan holder 63 is protruded on the upper surface and lower surface ofthe fan cover 64. The fan cover 64 is screwed at both sides with thehook 66 engaged with the groove 65 of the fan holder 63.

With the conventional liquid crystal projector device, an exhaust systemconsists of one exhaust fan placed toward the lamp unit 4. Therefore,the exhaust system discharges high temperature air around the lamp unit4, so that a user could feel uncomfortable when touching the exhaust.

With the liquid crystal projector device of the present invention,because the first exhaust fan 61 included in the exhaust system 6 isplaced toward the lamp unit 4 as shown in FIG. 2, the first exhaust fan61 draws high temperature air emitted from the lamp unit 4. On the otherhand, the second exhaust fan 62 draws lower temperature air than that ofthe air drawn by the first exhaust fan 61 because the second exhaust fan62 is placed toward the power unit 9, which is placed in an areadeviating from the lamp unit 4.

Because the exhaust directions of both exhaust fans 61, 62 intersecteach other, the air drawn from the first exhaust fan 61 and the airdrawn from the second exhaust fan 62 are mixed and then discharged fromthe vent 14. Consequently, the exhaust temperature is lower than that ofthe conventional projector device.

The more increases the intersection angle between the exhaust directionof the first exhaust fan 61 and the exhaust direction of the secondexhaust fan 62, the larger is a necessary space inside the casing 1 formounting both exhaust fans 61, 62. Accordingly, in order to find theintersection angle between the exhaust direction of the first exhaustfan 61 and the exhaust direction of the second exhaust fan 62 that givesthe maximum exhaust temperature-lowering effect, an experiment wasconducted where variations in exhaust temperature are measured with theintersection angle as a parameter. The result is that the intersectionangle within a range of 40 degrees to 60 degrees gives the maximumexhaust temperature-lowering effect.

That is, if the intersection angle is smaller than 40 degrees, then theair drawn from both exhaust fans 61, 62 is discharged withoutsufficiently mixed. Consequently, high temperature air is dischargedfrom the first exhaust fan 61 side of the exhaust system 6, and lowtemperature air is discharged from the second exhaust fan 62 side.

In contrast, when the intersection angle is 40 degrees to 60 degrees,the high temperature air drawn from the first exhaust fan 61 and the lowtemperature air drawn from the second exhaust fan 62 are sufficientlymixed. Consequently, the exhaust temperature is lower.

However, if the intersection angle is greater than 60 degrees, thelowering degree of the exhaust temperature relative to the increase ofthe intersection angle is smaller than in the case where theintersection angle is 40 degrees to 60 degrees. If the intersectionangle approximates 90 degrees, then the high temperature air drawn fromthe first exhaust fan 61 and the low temperature air drawn from thesecond exhaust fan 62 hit each other. This inhibits a smooth rearwardflow of air, preventing sufficient exhaust effect from being achieved.

Accordingly, in the present embodiment, the intersection angle betweenthe exhaust direction of the first exhaust fan 61 and the exhaustdirection of the second exhaust fan 62 is set to 40 degrees. The firstexhaust fan 61 and the second exhaust fan 62 are each attached with aninclination angle of 20 degrees relative to the right wall surface ofthe casing 1. This allows the exhaust temperature to be lowered whileminimizing enlargement of the device due to an increased mounting spacefor the exhaust system.

Actual measurement of the exhaust temperature and noise of the exhaustsystem 6 of the present embodiment reveals that even if both exhaustfans 61, 62 have revolutions less than conventional ones, the exhausttemperature is lowered by approximately 10° C., and the noise occurringfrom the exhaust system 6 can be reduced by 2 dB.

Further, the liquid crystal projector device of the present inventionhas a low power consumption mode where the power consumption is reducedby lowering the intensity of the light emitted from the lamp unit 4.When the low power consumption mode is set, the noise occurring from theexhaust system 6 can be further reduced by reducing the revolutions ofthe first and second exhaust fans 61, 62.

The present invention is not limited to the foregoing embodiment inconstruction but can be modified variously by one skilled in the artwithout departing from the spirit of the invention as set forth in theappended claims.

1. A projector device comprising a casing having disposed therein alight source and an optical system for receiving light from the lightsource to generate image light, the casing having a wall surface havingattached thereto an exhaust system for cooling an inside of the casing,the exhaust system comprising a first exhaust fan and a second exhaustfan, which stand along the wall surface of the casing, both exhaust fansbeing placed with the directions of their rotation axes intersectingeach other so that their exhaust directions intersect each other, thefirst exhaust fan having an inlet direction thereof toward the lightsource while the second exhaust fan having an inlet direction thereoftoward an area deviating from the light source, air discharged from bothexhaust fans is mixed since the exhaust directions intersect each other.2. The projector device according to claim 1, wherein an intersectionangle between the direction of the rotation axis of the first exhaustfan and the direction of the rotation axis of the second exhaust fan isset in a range of 40 degrees to 60 degrees.
 3. The projector deviceaccording to claim 1, wherein the first exhaust fan and the secondexhaust fan are each attached with an inclination angle relative to thewall surface of the casing.
 4. The projector device according to claim1, wherein the second exhaust fan is placed with the inlet directiontoward a power unit arranged in a position spaced apart from the lightsource.
 5. The projector device according to claim 1, wherein theprojector device is adapted to change intensity of the light emittedfrom the light source to a plurality of levels, and comprises controlmeans for variably setting revolutions of the first exhaust fan and/orthe second exhaust fan depending on the intensity of the light.